In the discussion that follows, reference is made to certain structures and/or methods. However, the following references should not be construed as an admission that these structures and/or methods constitute prior art. Applicants expressly reserve the right to demonstrate that such structures and/or methods do not qualify as prior art.
According to the American Diabetes Association, diabetes is the fifth-deadliest disease in the United States and kills more than 213,000 people a year, the total economic cost of diabetes in 2002 was estimated at over $132 billion dollars. One out of every 10 health care dollars is spent on diabetes and its complications. The risk of developing type I juvenile diabetes is higher than virtually all other chronic childhood diseases. Since 1987 the death rate due to diabetes has increased by 45 percent, while the death rates due to heart disease, stroke, and cancer have declined.
A critical component in managing diabetes is frequent blood glucose monitoring. Currently, a number of systems exist for self-monitoring by the patient. Most fluid analysis systems, such as systems for analyzing a sample of blood for glucose content, comprise multiple separate components such as separate lancing, transport, and quantification portions. These systems are bulky, and often confusing and complicated for the user. The systems require significant user intervention.
Technology development in the field of self-monitoring of blood glucose has placed the burden of acquiring sufficient blood for conducting a test on the user of the technology. Historically, diabetics have been taught to lance their finger tips to produce blood for conducting the test. Ironically, the fingers are not only one of the most sensitive body parts to pain, but they also are among the areas of skin that are most highly perfused with blood. Earlier versions of consumer-oriented self-monitoring products usually required many microliters of blood, and the finger tips provided a reasonably convenient area to lance that would be most likely to produce the required volume of blood.
More recently, some self-monitoring systems offer the option to the user to test at alternate sites such as the palm, forearm, or thigh. While these sites are generally known to be significantly less sensitive to the pain associated with lancing, the adoption of alternate site testing has been limited for at least four reasons: (1) only a few meter products have been approved by the FDA for testing at alternate sites at this time; (2) many testers do not know that they can use their device at the alternate sites; (3) many testers find it relatively difficult to express sufficient blood at the alternate sites to perform a test; (4) data published in medical literature on some of the meters shows that there may be a distinct difference between glucose levels measured at alternate sites relative to the finger, particularly when glucose levels are falling and/or the subject may be hypoglycemic. Consequently, there is a perception by the medical community that there may be an increased risk for delayed or improper treatment by the diabetic if they act only on the basis of glucose levels measured from alternate sites. Thus, the finger lancing site remains the most frequently used test site by far.
Lancing devices and the lancets themselves have also evolved somewhat over the past few decades. Some lancing mechanisms may produce relatively less pain by either (1) projecting the lancet in and out of the skin in a more straight path and thus reducing stimulation of percutaneous nerves which provide the pain stimulus; and (2) offering depth control in the lancing device so that the user may balance the expression of sufficient blood against the level of pain. Furthermore, lancet manufacturers offer a variety of lancet sizes, lengths, and tip bevel patterns with some companies claiming that their lancet is less painful than others.
What remains clear is that the most testers, when lancing at the finger, often must put down the lancing device and apply pressure near the finger tip in order to produce sufficient blood for the test strip in the meter. Many instructions for use with conventional meter systems specifically prescribe that the user perform this “milking” process because without it, many will not spontaneously produce the required volume. Applicants have observed this phenomenon in the use of commonly available commercial sampling and meter systems. In a recent study, when a trained professional lanced the finger tips of 16 volunteer diabetic subjects at the maximum depth setting on commercially available device under controlled conditions, only 15% of lanced sites spontaneously produced sufficient blood for the meter to accurately measure glucose levels.
Attempts have been made in the past to take steps toward automation of the testing process at alternate sites. Specifically, the Sof-Tact® System offered by Medisense in the early 2000s had the capability to test automatically at alternate sites without any user intervention, but only after each lancet and test strip had been manually loaded into the device. This meter is no longer available on the market.
A device similar to the Soft-Tact® device is disclosed in U.S. Patent Application Publication No. 2004/0138588 A1. This device attempts to integrate all the functions required to complete a glucose test into one device. This device however still requires the user to load a lancet and a test strip prior to each individual testing event, and fails to describe a catalyst (i.e.—mechanism to stimulate or enhance expression of blood from the lanced wound site) that ensures that a sufficient sample is expressed from the wound.
The device is described in U.S. Patent Application Publication No. 2005/0010134 A1, and U.S. Pat. No. 6,793,633 B2 uses a spring, or motor driven mechanism, to apply pressure around the target wound area. From the description it appears that the user must insert a new lancet and test strip assembly for each test.
Another disadvantage with conventional arrangements such as the ones referenced above is that they involve complex and sometimes ineffective mechanisms for tranferring blood or body fluid from the wound to a remote location for analysis. For example, many conventional arrangements and techniques utilize a solid lancet for creating a wound in the surface of the skin. After piercing the skin the lancet is retracted and a separate member, such as a tube, is positioned to transfer the blood or body fluid. Alternatively, an absorbent test strip is moved into position, manually or in an automated fashion, so that it absorbs the sample of blood or body fluid from the wound site. These arrangements and techniques are overly complex, and clearly rely upon the precise positioning of the tube or test strip to transfer the sample of blood or body fluid. When seeking to automate the sampling process, this precise positioning requires rather complex mechanical arrangements and controls that must operate under close tolerances. Such complex systems and arrangements are either costly, unreliable, or both.
Thus, conventional sampling devices and methods are overly reliant upon user intervention, such as milking, in order to consistently express a sufficient quantity of blood from the wound site, or are overly complex and/or lack reliabillity.
Moreover, while many diabetics continue to test their blood glucose levels with blood from the finger, testing at the alternate sites offers the advantage of significantly less pain when lancing the palm, forearm, etc. Thus, it would be advantageous to have an automatic and fully integrated meter constructed for sampling and/or testing at either the finger and the alternate sites.